A simplified Cluster – Based Gateway Selection Scheme for Multi-hop Vehicular Networks

Abstract

An integration of Vehicular Ad-hoc Network (VANET) and cellular network, e.g. LTE is a promising architecture for future machine-to-machine applications. This integration helps vehicles to have steady internet connection through cellular network and at same time can communicate with each other. However, dead spot areas and unsuccessful handover processes, due to vehicles high speed, can disturb the implementation of this kind of architecture. In this thesis, a Simplified Cluster –Based Gateway Selection (SCGS) Scheme for Multi-hop Vehicular networks is proposed. The main aim of this research is to enhance the integration between VANET and cellular network and to extend coverage in areas where there is no coverage. An enhanced version of Hybrid Wireless Mesh Protocol (E-HWMP) is proposed where it is a combination of IEEE802.11p and IEEE802.11s for multi-hop vehicular networks. E-HWMP provide a tradeoff between reactive and proactive gateway discovery solutions " consists of adjusting the scope for the gateway advertisement". The basic idea behind hybrid routing protocol is to use proactive routing mechanism inside the coverage zone at a certain time while utilizing a reactive routing mechanism on demand. An integrated simulation environment combined of VanetMobiSim and NS2 is used to simulate and evaluate the proposed scheme. An analytical model is also derived which is implemented by Matlab to optimize the proposed scheme. Simulation results show that, E-HWMP protocol performed better than Ad-hoc on demand Distance Vector (AODV) routing protocol and Hybrid Wireless Mesh Protocol (HWMP) routing protocol. Furthermore, SCGS through E-HWMP is compared with other cluster-based gateway selection algorithms i.e. CMGM and SGS that used in other related works; the result shows that SCGS scheme through E-HWMP protocol outperform the other cluster- based gateway selection schemes in terms of connection delay, control packet overhead, packet delivery ratio and overall throughput. Finally, results from analytical model are compared to simulation results to validate the approach of this thesis. Both analytical and simulation results agreed that: connectivity probability increases as average vehicle density increases and increased average vehicle speed degrades connectivity.